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mtd: rawnand: Fix return type of __DIVIDE() when called with 32-bit 

The __DIVIDE() macro checks whether it is called with a 32-bit or 64-bit
dividend, to select the appropriate divide-and-round-up routine.
As the check uses the ternary operator, the result will always be
promoted to a type that can hold both results, i.e. unsigned long long.

When using this result in a division on a 32-bit system, this may lead
to link errors like:

    ERROR: "__udivdi3" [drivers/mtd/nand/raw/nand.ko] undefined!

Fix this by casting the result of the division to the type of the
dividend.

Fixes: 8878b126df ("mtd: nand: add ->exec_op() implementation")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
This commit is contained in:
Geert Uytterhoeven 2018-05-14 12:49:37 +02:00 committed by Boris Brezillon
parent 90d6176333
commit 9f825e74d7
1 changed files with 11 additions and 5 deletions
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10
include/linux/mtd/rawnand.h
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@ -867,11 +867,17 @@ struct nand_op_instr {
* tBERS (during an erase) which all of them are u64 values that cannot be
* divided by usual kernel macros and must be handled with the special
* DIV_ROUND_UP_ULL() macro.
*
* Cast to type of dividend is needed here to guarantee that the result won't
* be an unsigned long long when the dividend is an unsigned long (or smaller),
* which is what the compiler does when it sees ternary operator with 2
* different return types (picks the largest type to make sure there's no
* loss).
*/
#define __DIVIDE(dividend, divisor) ({ \
sizeof(dividend) == sizeof(u32) ? \
(__typeof__(dividend))(sizeof(dividend) <= sizeof(unsigned long) ? \
DIV_ROUND_UP(dividend, divisor) : \
DIV_ROUND_UP_ULL(dividend, divisor); \
DIV_ROUND_UP_ULL(dividend, divisor)); \
})
#define PSEC_TO_NSEC(x) __DIVIDE(x, 1000)
#define PSEC_TO_MSEC(x) __DIVIDE(x, 1000000000)